Pharmacologic studies with cefaclor, a new oral cephalosporin.

Cefaclor, a new oral cephalosporin, was administered to 18 normal human volunteers in either single or multiple doses of 250 and 500 mg. Mean serum concentrations of 6.09 and 12.8 microgram/ml were achieved 1 hour after single oral doses of 250 and 500 mg, respectively. The serum concentrations declined rapidly and no drug was detected at 4 hours. Very high concentrations of cefaclor were found in urine during the first 8 hours after ingestion of the drug. Forty-three per cent of the total dose was excreted in urine during the first 8 hours. There was no accumulation of drug in serum during the multiple-dose studies.